Re: [Xen-devel] [PATCH] ignore guest writes to read only memory regions or memory holes in EPT

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

After looking at the documentation I don't think using
__get_instruction_length() here is valid, i.e. you need to decode the
instruction in order to be able to skip it. Otherwise, could you have
your doc folks update the documentation (24.2.4) accordingly?

Jan

>>> "Li, Xin" <xin.li@xxxxxxxxx> 23.10.09 09:26 >>>
ignore guest writes to read only memory regions or memory holes in EPT.

This patch prevents domain crash when running memtest86 with EPT.

Signed-off-by: Xin Li <xin.li@xxxxxxxxx>

diff -r 37829fd7c1e3 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Wed Oct 21 16:08:28 2009 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Fri Oct 23 23:21:27 2009 +0800
@@ -2184,6 +2184,17 @@
         return;
     }

+    /* Ignore writes to:
+     *     1. read only memory regions;
+     *     2. memory holes. */
+    if ( (qualification & EPT_WRITE_VIOLATION)
+         && (((gla_validity == EPT_GLA_VALIDITY_MATCH) && (t == p2m_ram_ro))
+             || (mfn_x(mfn) == INVALID_MFN)) ) {
+        int inst_len = __get_instruction_length();
+        __update_guest_eip(inst_len);
+        return;
+    }
+
     /* Everything else is an error. */
     gla = __vmread(GUEST_LINEAR_ADDRESS);
     gdprintk(XENLOG_ERR, "EPT violation %#lx (%c%c%c/%c%c%c), "


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel